Year % 2009 12.7087219554461 2010 11.9573349173135 2011 12.5956019975254 2012 12.993306020068 2013 12.5403877289777 2014 12.5184598126835 2015 12.8540035694888 2016 13.1515333766196 2017 12.871175027192 2018 12.1610965391164 2019 12.4301031322425 2020 12.3081785895039 2021 11.8260714068531 2022 11.2867668498435